In a legal dispute, a German court must also decide on foreign law insofar as this is relevant. This obligation follows from Section 293 ZPO, according to which the court is not limited to the evidence provided by the parties, but is rather authorized to use other sources of information and to order the necessary measures for the purpose of such use.

The court must determine the foreign law itself ex officio. How the court obtains this knowledge is at its own discretion. Free evidence applies, i.e. the court may make use of all evidence and sources of knowledge. The court's options also include obtaining an expert opinion on foreign law. However, the expert's task is limited to answering the questions of evidence on foreign law posed by the court. The determination, interpretation and application of the private international law applicable in Germany (IPR) as well as the decision of the specific case (i.e. determination of the facts and subsumption) by applying foreign law always remain the original tasks of the court.

If foreign law is relevant to the decision, the court must discuss this with the parties (right to be heard) and give them the opportunity to present their views on its determination and content. If the court has formed a preliminary opinion on the content of the foreign law, e.g. based on its own research, it shall inform the parties of this opinion (Hamburg Guidelines (2023), Art. 2 § 2 no. 2).

The parties to the legal dispute may assist the court in determining foreign law, but are generally not obliged to do so beyond their general duty to support the proceedings or cooperate. Since foreign legal norms are treated as legal principles and not as facts, the principles of the burden of presentation and proof do not apply in this respect (Hamburg Guidelines (2023), Art. 1 § 1 no. 3 with reference to BGH, decision of 24.08.2022 - XII ZB 268/19). For reasons of procedural tactics, each party should nevertheless make submissions on foreign law. For this reason alone, it makes sense to be represented in an international legal dispute by experienced, specialized lawyers who can confidently and competently conduct the legal dispute and convince the court.

According to established case law of the BGH, foreign law is to be determined and applied by the competent court in the same way as it is or would be applied by the courts of the country concerned (see BGH, judgment of 05.07.2023 - IV ZR 375/21 para. 27).

In the opinion of the BGH, the application of foreign law is not subject to appeal (with reference to Section 560 ZPO in conjunction with Section 545 ZPO). The court of appeal is generally bound by the findings of the court of appeal regarding the content of foreign law. In other words: German law is revisable, foreign law is not. However, the determination of foreign law is very much subject to review by the highest court (see BGH, judgment of 05.07.2023 - IV ZR 375/21 para. 24).

The "Hamburg Guidelines on the Determination and Application of Foreign Law in German Proceedings" (Hamburg Guidelines), developed in an intensive exchange between practitioners and academics and published by the Max Planck Institute for Comparative and International Private Law in Hamburg, support courts, experts and parties (including their representatives) in dealing with foreign law in international legal disputes. They present the relevant legal framework in a compact form and provide a large number of practical recommendations for action(Michaels/Schmidt, Die Hamburger Leitlinien zur Ermittlung und Anwendung ausländischen Rechts in deutschen Verfahren, NJW 2024, 24 with further information on the background, content and outlook).

The Hamburg Guidelines are aimed at proceedings before civil courts, but in
principle they are also applicable to other cases in which German courts
or authorities (e.g. financial courts, criminal courts, asylum authorities, tax authorities, registry offices) have to apply foreign law (Hamburg Guidelines (2023), preliminary remarks).

The Hamburg Guidelines say nothing about the international jurisdiction of German courts, as the courts can and must answer this question independently on the basis of the relevant legal sources (e.g. Brussels Ia Regulation, Brussels IIb Regulation, Sections 97 et seq. of the German Family Proceedings Act) (Hamburg Guidelines (2023), preliminary remarks).

In summary, it can be said that the Hamburg guidelines are a helpful tool for practitioners.

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The Hamburg guidelines are published under the Creative Commons license CC-BY 4.0 license. The publisher is the Max Planck Institute for Comparative and International Private Law, Hamburg. The authors are Prof. Dr. Ralf Michaels and Priv.-Doz. Dr. Jan Peter Schmidt. The Hamburg Guidelines are available here available here.